The present invention pertains to determining the state of battery life of a starting, lighting and ignition battery.
Numerous attempts have been made to ascertain the state of charge of a starting, lighting and ignition xe2x80x9cSLIxe2x80x9d battery. It is particularly important to know the state of the charge of the battery so that it can be readily determined whether the battery will be useful for the immediate future. The state of charge can frequently be required to take into account the life of the battery, namely the number of cranks that the battery has been exposed to as well as the temperature that a battery has been exposed to.
U.S. Pat. No. 4,234,840 column 1, lines 11 through 20, relies upon such devices as specific gravity metering device, or ampere watt-hour metering device. The patent also took into account the terminal voltage of the batteries while energizing their load circuits.
U.S. Pat. No. 4,560,937 pertains to a battery state of charge metering method which utilized a digital integrator including a plurality of digital stages comparable to store a numeric value in binary digital form which is indicative of the state of charge.
U.S. Pat. No. 5,214,385 utilized polarization voltage to determine the charge state of a battery. A test signal is characterized by a least one transition to a charging voltage which is retained for a time sufficient to allow a polarization voltage to develop across the cell.
U.S. Pat. No. 5,352,968 pertains to a battery charge state determination which is derived from the battery voltage corrected for temperature and series resistance effects.
U.S. Pat. No. 5,596,260 pertains to an apparatus and method for determining a charge of a battery whereby initially a discharge curve specifying the battery""s voltage as a function of time is determined. The battery discharge model is updated by applying Bayes theorem to the old discharge model and the voltage probability distribution.
U.S. Pat. No. 5,598,088 pertains to a method for determining the charge of a battery in which a charge balance is carried out by evaluating the charging current and the discharging current. This is checked with the aid of the measured battery open-circuit voltage and thereafter corrected. Additional variables such as battery temperature and time are likewise taken into account.
None of the references take into account the health of an SLI battery which electronically monitors the physical parameters it is exposed to while also measuring key operating features and displaying the state of health of the battery.
A method of determining the state of battery life of a starting, lighting and ignition (SLI) battery comprising; 1) determining the number of starting engine cranks the battery has performed and comparing that number with a desired number for starting engine cranks to ascertain a state of health of the battery, calculated as a percentage of the desired number; 2) determining the percentage of battery life diminished due to battery exposure to a maximum temperature and the minimum state of charge the battery has been exposed to at that temperature, calculated as a decrease from 100 percent; and 3) calculating the value, such as, the lower of the values, of step 1 or step 2 thereby determining the state of the battery life.
Also described is an apparatus for determining the state of battery life of a starting, lighting and ignition (SLI) battery comprising; 1) a first register for storing a first numeric value which is obtained by determining the number of starting engine cranks the battery has performed and comparing that number with a desired number for starting engine cranks to ascertain the state of health of the battery, calculated as a percentage of the desired number; 2) a second register storing a second numeric value which is obtained by determining the percentage of battery life diminished due to battery exposure to a maximum temperature and the minimum state of charge the battery has been exposed to at that temperature, calculated as a decrease from 100 percent; and 3) means for calculating the difference between the values of the first register and the second register to determine the state of the battery life.